Generally speaking, in the UK college is somewhere you go when you haven't quite reached the grade required for a University level education, but desire to gain a vocational qualification of some sort. These generally span from diplomas in anything from hairdressing to automotive repair.

When I moved to the US I was surprised when people asked me about my college, as I have some degree of pride in going to a University instead of a college, as the former given you a higher quality of education the the latter.

As far as I can remember, the difference between the two is that a University can award degrees, while a college can only award diplomas.